A shift control system has been known that switches the shift range of an automatic transmission under electrical control in response to manipulation of a shift lever by a driver. Such a shift control system is disclosed in Japanese Patent Laying-Open No. 2004-308752 (Patent Document 1). The disclosed shift control system can appropriately control rotation of an actuator that drives a shift switch mechanism for switching the shift range of a transmission, using an encoder capable of detecting only the information about relative position.
The shift control system disclosed in Japanese Patent Laying-Open No. 2004-308752 performs control in such a manner that causes the actuator to rotate and thereby causes a wall of a detent plate to be pressed against a roller of a detent spring (hereinafter also referred to as “press control” or “wall press control”), and the position where the wall and the roller come into contact with each other is detected so as to detect the wall position of the detent plate. This wall position is used as a reference position. Therefore, the rotation of the actuator can be appropriately controlled even when the encoder capable of detecting only the information about relative position is used.